to a host which looks like a standard storage controller SCSI target. On the VPLEX back end, the VPLEX provides an interface to a physical storage controller that act like a host, essentially like a SCSI initiator. A VPLEX cluster consists of one or more pairs of directors (up to 4 pairs). Any director from any engine can failover to any other director in the cluster in the case of hardware or path failure. References Dell EMC Storage virtualization